Melatonin implantation improved the egg-laying rate and quality in hens past their peak egg-laying age

Abstract

The egg-laying rates of hens approximately 470 days of age exhibited a positive correlation to blood melatonin levels. The hens with an egg-laying rate <30%, 30~90% and ≥90% had blood melatonin levels of 5.8 ± 2.6, 74.0 ± 32.9 and 445.9 ± 115.3 ng/ml, respectively. When 10 mg of melatonin was implanted into the hens at 300, 360, 470 and 550 days of age, the egg-laying rates increased 4.63 ± 0.46%, 8.38 ± 1.45%, 4.93 ± 0.85% and 7.93 ± 0.91%, respectively, compared to that of the controls. Melatonin implantation in hens at 300–470 days of age was observed to enhance egg production and reduce the rate of appearance of sharpei eggs. Melatonin (10 mg) implanted in hens 360 days of age did not influence the blood levels of progesterone (P4) or the gene expression levels of ovarian follicle stimulating hormone receptor (FSHR), luteinizing hormone receptor (LHR), oestradiol receptor alpha (ERα), superoxide dismutase 2 (SOD2) or melatonin receptor 1 (MT1). In contrast, melatonin significantly elevated the serum oestradiol-17β (E2) content, down-regulated the gene expression of gonadotropin-inhibitory hormone receptor (GnIHR), and enhanced the expression of melatonin receptor 2 (MT2). This result indicates that the improved egg-laying rate by melatonin was the result of increased serum oestradiol and decreased ovarian GnIHR. These alterations may be mediated by MT2 activation.

RNAi-mediated knockdown of MTNR1B without disrupting the effects of melatonin on apoptosis and cell cycle in bovine granulose cells

“…On the other hand, the role of melatonin in regulating porcine GCs proliferation and apoptosis are predominantly mediated by MTNR1B ( He et al, 2016c ). Melatonin increases serum estradiol and decreases ovarian Gonadotropin-inhibitory hormone receptor expression, thus improves hens egg-laying rates by activation of MTNR1B ( Jia et al, 2016 ). However, MTNR1A and MTNR1B may act in a complementary way to modulate the cell apoptosis.…”

The role of Melatonin receptor MTNR1A in the action of Melatonin on bovine granulosa cells

“…On the other hand, MTNR1B was reported to predominantly mediate the in vitro effect of Melatonin on porcine GC proliferation, apoptosis, and steroidogenesis (He, Deng, et al, ). Melatonin also improved egg‐laying rates by hens as a result of MTNR1B activity, leading to increased serum estradiol and decreased ovarian GNIHR (Gonadotropin‐inhibitory hormone receptor) expression (Jia et al, ). Together, these findings suggest that both MTNR1A and MTNR1B participate in the regulation of complex reproductive mechanisms that also involve the hypothalamic‐pituitary‐gonadal axis (Dubocovich & Markowska, ).…”

Seasonal Reproduction in Vertebrates: Melatonin Synthesis, Binding, and Functionality Using Tinbergen’s Four Questions

“…In avian ovaries and follicles, melatonin receptors have been sequenced varied stages of follicular development [ 132 ] and egg laying [ 316 ]. Melatonin implantation (10 mg) to chickens 300–470 days of age increased egg-laying rate [ 316 ].…”

“…In avian ovaries and follicles, melatonin receptors have been sequenced varied stages of follicular development [ 132 ] and egg laying [ 316 ]. Melatonin implantation (10 mg) to chickens 300–470 days of age increased egg-laying rate [ 316 ]. Chickens supplemented with melatonin had no significant difference relative to controls with LH-receptor, FSH-receptor, estradiol receptor alpha (ERα), nor MT2 receptor expression in the ovaries [ 316 ].…”